package cn.jc.springframework.beans.factory.support;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import cn.jc.springframework.beans.BeansException;
import cn.jc.springframework.beans.PropertyValue;
import cn.jc.springframework.beans.factory.*;
import cn.jc.springframework.beans.factory.config.*;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

/**
 * @Description:
 * @author: JC
 * @date: 2022/5/31 18:43
 */
public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFactory implements AutowireCapableBeanFactory {
    private InstantiationStrategy instantiationStrategy = new CglibSubclassingInstantiationStrategy();

    @Override
    protected Object createBean(String beanName, BeanDefinition beanDefinition, Object[] args) throws BeansException {

        Object bean = null;
        try {
            // 判断是否返回代理 Bean 对象
            bean = resolveBeforeInstantiation(beanName, beanDefinition);
            if (bean != null) {
                return bean;
            }

            bean = createBeanInstance(beanDefinition, beanName, args);
            // 给 Bean 填充属性
            applyPropertyValues(beanName, bean, beanDefinition);

            // 执行 Bean 的初始化方法和 BeanPostProcessor 的前置和后置处理方法
            bean = initializeBean(beanName, bean, beanDefinition);
        } catch (Exception e) {
            throw new BeansException("创建bean失败，AbstractAutowireCapableBeanFactory.createBean()", e);
        }
        // 注册实现了 DisposableBean 接口的 Bean 对象
        registerDisposableBeanIfNecessary(beanName, bean, beanDefinition);

        // 判断 SCOPE_SINGLETON、SCOPE_PROTOTYPE
        if(beanDefinition.isSingleton()){
            registerSingleton(beanName, bean);
        }

        return bean;
    }

    protected Object resolveBeforeInstantiation(String beanName, BeanDefinition beanDefinition) {
        Object bean = applyBeanPostProcessorsBeforeInstantiation(beanDefinition.getBeanClass(), beanName);
        if (null != bean) {
            bean = applyBeanPostProcessorsAfterInitialization(bean, beanName);
        }
        return bean;
    }
    protected Object applyBeanPostProcessorsBeforeInstantiation(Class<?> beanClass, String beanName) {
        for (BeanPostProcessor beanPostProcessor : getBeanPostProcessors()) {
            if (beanPostProcessor instanceof InstantiationAwareBeanPostProcessor) {
                Object result = ((InstantiationAwareBeanPostProcessor) beanPostProcessor).postProcessBeforeInstantiation(beanClass, beanName);
                if (null != result) return result;
            }
        }
        return null;
    }

    private void registerDisposableBeanIfNecessary(String beanName, Object bean, BeanDefinition beanDefinition) {
        // 非 Singleton 类型的 Bean 不执行销毁方法
        if(!beanDefinition.isSingleton())return;

        if (bean instanceof DisposableBean || StrUtil.isNotEmpty(beanDefinition.getDestroyMethodName()))
            registerDisposableBean(beanName, new DisposableBeanAdapter(bean, beanName, beanDefinition));
    }

    private Object initializeBean(String beanName, Object bean, BeanDefinition beanDefinition) {

        // 执行aware感知接口方法 invokeAwareMethods
        if(bean instanceof Aware){
            if(bean instanceof BeanFactoryAware){
                ((BeanFactoryAware)bean).setBeanFactory(this);
            }
            if (bean instanceof BeanClassLoaderAware) {
                ((BeanClassLoaderAware)bean).setBeanClassLoader(getBeanClassLoader());
            }
            if (bean instanceof BeanNameAware) {
                ((BeanNameAware)bean).setBeanName(beanName);
            }

        }

        // 1. 执行 BeanPostProcessor Before 处理
        Object wrappedBean = applyBeanPostProcessorsBeforeInitialization(bean, beanName);

        // 执行 Bean 对象的初始化方法
        try {
            invokeInitMethods(beanName, wrappedBean, beanDefinition);
        } catch (Exception e) {
            throw new BeansException("Invocation of init method of bean[" + beanName + "] failed", e);
        }

        // 2. 执行 BeanPostProcessor After 处理
        wrappedBean = applyBeanPostProcessorsAfterInitialization(bean, beanName);

        return wrappedBean;
    }

    private void invokeInitMethods(String beanName, Object bean, BeanDefinition beanDefinition) throws Exception {
        // 1. 实现接口 InitializingBean
        if (bean instanceof InitializingBean) {
            ((InitializingBean) bean).afterPropertiesSet();
        }

        // 2. 配置信息 init-method {判断是为了避免二次执行销毁}
        String initMethodName = beanDefinition.getInitMethodName();
        if (StrUtil.isNotEmpty(initMethodName) && !(bean instanceof InitializingBean
                && "afterPropertiesSet".equals(initMethodName))) {

            Method initMethod = beanDefinition.getBeanClass().getMethod(initMethodName);
            if (initMethod == null) {
                throw new BeansException("Could not find an init method named '" +
                        initMethodName + "' on bean with name '" + beanName + "'");
            }
            initMethod.invoke(bean);
        }
    }

    @Override
    public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName) throws BeansException {
        Object result = existingBean;
        for (BeanPostProcessor beanPostProcessor : getBeanPostProcessors()) {
            Object current = beanPostProcessor.postProcessBeforeInitialization(result, beanName);
            if (current == null) {
                return result;
            }
            result = current;
        }
        return result;
    }

    @Override
    public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) throws BeansException {
        Object result = existingBean;
        for (BeanPostProcessor beanPostProcessor : getBeanPostProcessors()) {
            Object current = beanPostProcessor.postProcessAfterInitialization(result, beanName);
            if (current == null) {
                return result;
            }
            result = current;
        }
        return result;
    }

    protected Object createBeanInstance(BeanDefinition beanDefinition, String beanName, Object[] args){
    Constructor constructorToUse = null;
    Class beanClass = beanDefinition.getBeanClass();

    Constructor[] declaredConstructors = beanClass.getDeclaredConstructors();
    for (Constructor declaredConstructor : declaredConstructors) {
        if (null != args && declaredConstructor.getParameterTypes().length == args.length) {
            constructorToUse = declaredConstructor;
            break;
        }
    }
    return getInstantiationStrategy().instantiate(beanDefinition,beanName,constructorToUse,args);
    }

    /**
     * Bean 属性填充
     */
    protected void applyPropertyValues(String beanName, Object bean, BeanDefinition beanDefinition){

        try {
            PropertyValue[] propertyValues = beanDefinition.getPropertyValues().getPropertyValues();
            for (PropertyValue propertyValue : propertyValues) {
                String name = propertyValue.getName();
                Object value = propertyValue.getValue();
                // 如果遇到BeanReference属性就递归获取Bean实例
                if(value instanceof BeanReference){
                    // A 依赖 B，获取 B 的实例化
                    BeanReference beanReference = (BeanReference)value;
                    value = getBean(beanReference.getBeanName());
                }
                // 属性填充
                BeanUtil.setFieldValue(bean, name, value);
            }
        } catch (BeansException e) {
            throw new BeansException("Error setting property values：" + beanName);
        }
    }

    public InstantiationStrategy getInstantiationStrategy() {
        return instantiationStrategy;
    }

    public void setInstantiationStrategy(InstantiationStrategy instantiationStrategy) {
        this.instantiationStrategy = instantiationStrategy;
    }



}
